CN109399584B - Hexagonal-tube-shaped carbon nitride and preparation method and application thereof - Google Patents

Hexagonal-tube-shaped carbon nitride and preparation method and application thereof Download PDF

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CN109399584B
CN109399584B CN201811207245.6A CN201811207245A CN109399584B CN 109399584 B CN109399584 B CN 109399584B CN 201811207245 A CN201811207245 A CN 201811207245A CN 109399584 B CN109399584 B CN 109399584B
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杨萍
江志翔
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University of Jinan
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Abstract

The invention discloses hexagonal tubular carbon nitride and a preparation method and application thereof, wherein the preparation method comprises the following steps: heating the nitrogen-containing organic precursor to 450-600 ℃ for calcining to obtain blocky carbon nitride; dispersing the blocky carbon nitride in water, and carrying out hydrothermal reaction at 150-200 ℃ to obtain floccules; and heating the floccule to 450-750 ℃ for calcining to obtain hexagonal tubular carbon nitride. The method is simple and easy to implement, low in price and good in repeatability, and has a great inspiring significance for the synthesis of tubular materials. The hexagonal tubular carbon nitride obtained by the invention has special morphology, is extremely innovative, has uniform size distribution, has higher specific surface area compared with the traditional two-dimensional morphology such as carbon nitride nanosheets, and is beneficial to providing more active sites and improving the reaction activity. In the aspect of hydrogen production by visible light photocatalysis, the excellent photocatalysis property is beyond the reach of common flaky carbon nitride.

Description

Hexagonal-tube-shaped carbon nitride and preparation method and application thereof
Technical Field
The invention relates to carbon nitride with a special micro-morphology, in particular to hexagonal tubular carbon nitride and a preparation method thereof, and also relates to application of the hexagonal tubular carbon nitride as a visible light photocatalytic hydrogen production catalyst, belonging to the technical field of semiconductor materials and preparation thereof.
Background
Carbon nitride, an organic semiconductor, is an extremely excellent photocatalyst because it has a relatively appropriate band gap structure (2.7 eV). In recent years, the method is continuously modified, and comprises ion doping, heterojunction, morphology change and the like. Comparing a series of documents, the tubular carbon nitride material has the most excellent hydrogen production property by visible light photocatalysis. This is mainly due to the fact that the presence of the tubular morphology facilitates the movement of electrons along the tube axis, thus accelerating the electron-hole separation. However, the synthesis of tubular carbon nitride is mostly limited to the template method, and if the template is not completely removed, the properties of the carbon nitride are greatly influenced. Therefore, a series of methods, such as a soft template method and the like, are explored to improve the method. However, it is still difficult to realize the non-template method, especially to precisely synthesize uniform tubular carbon nitride by the non-template method.
Patent 201810195607.8 discloses a cobalt ion doped carbon nitride hollow quadrangular prism, which is prepared by the following steps: preparing a nitrogen-containing organic precursor, divalent cobalt salt and water into a solution, heating the solution to boil, cooling and crystallizing, and calcining the obtained crystal to obtain the cobalt-based catalyst. The method adopts a non-template method to prepare the carbon nitride, realizes the appearance through ion induction, and the obtained carbon nitride is hollow quadrangular prism with a quadrangular cross section.
Patent CN201610219084.7 discloses a carbon nitride nanotube, the preparation method is: preparing urea solution from urea and sodium bicarbonate according to a molar ratio, and then cooling the solution to integrally freeze the solution to obtain uniform white blocky solid; then the white block solid is quickly transferred into a vacuum freeze dryer, freeze-dried under the conditions that the vacuum degree is less than or equal to 20Pa and the freezing temperature is less than or equal to minus 50 ℃, and then calcined in a nitrogen atmosphere furnace to obtain the catalyst. The method adopts a soft template method to prepare the carbon nitride, and CO generated by the decomposition of sodium bicarbonate2The nanotube appearance is realized, the obtained nanotube is hollow tubular, and the cross section is circular or similar to circular.
Disclosure of Invention
At present, no report related to hexagonal tubular carbon nitride exists, and the invention aims to provide hexagonal tubular carbon nitride so as to expand the microscopic morphology of the carbon nitride, wherein the carbon nitride with the special morphology has uniform size distribution, good morphology repeatability and excellent visible light photocatalysis hydrogen production property.
The invention also aims to provide a preparation method and application of the hexagonal tubular carbon nitride, the method has the advantages of simple operation process, low cost, good repeatability and convenience for industrial production, and the obtained product has uniform size, large specific surface area and excellent hydrogen production property by visible light photocatalysis and can be used as a catalyst for hydrogen production by visible light photocatalysis.
The specific technical scheme of the invention is as follows:
the hexagonal tube-shaped carbon nitride has the effective component of carbon nitride, is in the shape of a hexagonal tube and can be also called as a hollow hexagonal prism, and the cross section of the outer wall (also called as the outer side wall) and the cross section of the inner wall (also called as the inner side wall) of the hexagonal tube are both hexagonal.
Further, the hexagonal tubular carbon nitride has a length of 50 to 70 μm, a side length of a cross section of an inner wall of 400 to 600 nm, and a wall thickness of 100 to 200 nm.
The invention also provides a preparation method of the hexagonal tubular carbon nitride, which comprises the following steps:
(1) heating the nitrogen-containing organic precursor to 450-600 ℃ for calcining to obtain blocky carbon nitride;
(2) dispersing the blocky carbon nitride in water, and carrying out hydrothermal reaction at 150-200 ℃ to obtain floccules;
(3) and heating the floccule to 450-750 ℃ for calcining to obtain hexagonal tubular carbon nitride.
Further, in the step (1), the nitrogen-containing organic precursor is melamine, dicyandiamide or urea. The nitrogen-containing organic precursor is heated to 450-600 ℃ to carry out preliminary thermal polycondensation on the nitrogen-containing organic precursor to form blocky carbon nitride. The calcination is carried out in an air atmosphere, preferably, the temperature is increased to 450-600 ℃ at the temperature increasing speed of 2-5 ℃/min, and the performance of the obtained product is similar within the temperature increasing speed range. Preferably, the calcination time is 2-4 h.
Further, in the step (2), the bulk carbon nitride is dispersed in water, and is heated to perform a hydrothermal reaction, wherein the hydrothermal reaction is performed in a closed environment, and the reaction vessel may be a reaction kettle. In the reaction process, certain self reaction pressure exists in the kettle along with the rise of the temperature. The purpose of the hydrothermal reaction is to enable the oxazine ring network of the bulk carbon nitride to be transversely cut and self-assembled into white floccules, wherein the micro appearance of the white floccules is a one-dimensional polygonal rod, and the time of the hydrothermal reaction is preferably 5-15 h. Preferably, the mass ratio of the massive carbon nitride to the water is 0.02-0.05: 1. when the water consumption is too small, the block carbon nitride can not complete hydrolysis self-assembly, and the hexagonal tubular shape can not be obtained; when the water consumption is excessive, the block carbon nitride is completely hydrolyzed, self-assembly cannot be completed, and the hexagonal tubular shape cannot be obtained.
Further, in the step (2), after the hydrothermal reaction, the obtained floccule is washed with water, freeze-dried in vacuum, and then subjected to the step (3) for the second calcination.
Furthermore, in the step (3), the floccule formed by hydrothermal reaction is heated and calcined, and then is subjected to second thermal polycondensation, so that a hexagonal tubular carbon nitride structure is finally formed due to the diffusion effect. The calcination is carried out under the protection of gas, and the protection gas is nitrogen or inert gas. During calcination, the temperature is preferably raised to 450-750 ℃ at the temperature rise speed of 1-10 ℃/min, and the performance of the obtained product is similar within the temperature rise speed range. The calcination time is preferably 1-4 h. The temperature of the second thermal polycondensation may be the same as or different from the temperature of the first thermal polycondensation, and is not related to each other.
In the preparation method, the carbon-nitrogen-containing precursor is used as a raw material and is subjected to preliminary thermal condensation polymerization to form blocky carbon nitride, the blocky carbon nitride is hydrolyzed and self-assembled under the hydrothermal condition to form a one-dimensional polygonal rod-shaped precursor (namely white floccule), and the one-dimensional polygonal rod-shaped precursor is subjected to secondary thermal condensation polymerization to obtain the carbon nitride with the special hexagonal tubular shape due to the diffusion effect. The hexagonal tubular carbon nitride has a length of about 50 to 70 μm, and SEM images of the obtained product are shown in FIGS. 2 and 3, and it can be seen that the hexagonal tubular carbon nitride is hexagonal and uniformly distributed. The product of the invention has special appearance, and the specific surface area test result shows that the product has larger specific surface area than the carbon nitride nano-sheet. Therefore, the method has great instructive significance for the synthesis of the tubular material with high specific surface area, and can realize more applications by compounding the tubular material with other substances.
Experiments prove that the hexagonal tubular carbon nitride has excellent visible light photocatalytic hydrogen production property and is beneficial to application in the photocatalytic hydrogen production industry in the future, so that the invention also provides application of the hexagonal tubular carbon nitride as a photocatalytic hydrogen production catalyst. The hydrogen production capability of the photocatalyst is obviously improved compared with that of flaky carbon nitride.
The method takes blocky carbon nitride synthesized at different temperatures as a raw material for the first time, and synthesizes the one-dimensional hexagonal tubular carbon nitride material through hydrothermal reaction and calcination in a gas protection atmosphere. The hexagonal tubular carbon nitride obtained by the invention has special morphology, is extremely innovative, has uniform size distribution, has higher specific surface area compared with the traditional two-dimensional morphology such as carbon nitride nanosheets, and is beneficial to providing more active sites and improving the reaction activity. In the aspect of hydrogen production by visible light photocatalysis, the excellent photocatalysis property is beyond the reach of common flaky carbon nitride. In addition, the hexagonal tubular carbon nitride material can be effectively compounded with other substances, separation and transfer of photogenerated electron hole pairs are further promoted, properties such as photocatalysis are further improved, and application potential is shown in a plurality of fields such as photocatalysis.
Drawings
Fig. 1 is a Scanning Electron Microscope (SEM) photograph of the precursor prepared in example 1.
FIG. 2 is a Scanning Electron Microscope (SEM) photograph of hexagonal tubular carbon nitride at low magnification prepared in example 1.
FIG. 3 is a Scanning Electron Microscope (SEM) photograph of hexagonal tubular carbon nitride at high magnification prepared in example 1.
Fig. 4 is an X-ray diffraction pattern (XRD) of the precursor prepared in example 1 and hexagonal tubular carbon nitride.
Fig. 5 is a graph showing a nitrogen adsorption-desorption test (BET) change of hexagonal tubular carbon nitride prepared in example 1.
Fig. 6 is a visible light photocatalytic hydrogen production diagram of a hexagonal-tube-shaped carbon nitride sample prepared in example 1.
Fig. 7 is a Scanning Electron Microscope (SEM) photograph of the precursor prepared in example 5.
FIG. 8 is a Scanning Electron Microscope (SEM) photograph of hexagonal tubular carbon nitride prepared in example 5.
Fig. 9 is a Scanning Electron Microscope (SEM) photograph of the precursor prepared in example 6.
FIG. 10 is a Scanning Electron Microscope (SEM) photograph of hexagonal tubular carbon nitride prepared in example 6.
Fig. 11 is a Scanning Electron Microscope (SEM) photograph of the sample prepared in comparative example 1.
FIG. 12 is a Scanning Electron Microscope (SEM) photograph of a product obtained by a hydrothermal reaction in comparative example 2 in which the thermal polycondensation temperature of melamine is 650 ℃.
FIG. 13 is a Scanning Electron Microscope (SEM) photograph of a product obtained by hydrothermal reaction of comparative example 2 in which the thermal polycondensation temperature of melamine is 400 ℃.
FIG. 14 is a Scanning Electron Microscope (SEM) photograph of a product obtained after the secondary polycondensation at a thermal polycondensation temperature of 400 ℃ for melamine in comparative example 2.
FIG. 15 is a Scanning Electron Microscope (SEM) photograph of a product obtained by hydrothermal reaction in comparative example 6.
FIG. 16 is a Scanning Electron Microscope (SEM) photograph of a precursor obtained by hydrothermal reaction in comparative example 7.
FIG. 17 is a Scanning Electron Microscope (SEM) photograph of the final product obtained in comparative example 7.
Detailed Description
The present invention will be further illustrated by the following figures and examples, it being understood that the following descriptions are intended to illustrate the invention and are not intended to limit the scope thereof.
In the following examples, comparative processes for preparing lamellar carbon nitrides were as follows: 10g of melamine was subjected to thermal polycondensation at 650 ℃ for 4 hours to obtain carbon nitride in the form of a sheet having a thickness of about 60 nm and a size of about 5 μm.
In the following examples, the photocatalytic hydrogen production diagram of hexagonal tubular carbon nitride and tabular carbon nitride was completed by placing a carbon nitride catalyst in a sealed Pyrex reaction cell and irradiating with a 300W xenon lamp (CEL-HXF 300) equipped with a 420 nm filter, and the specific steps were: 0.01g of carbon nitride catalyst was dispersed in 50ml of an aqueous solution containing 10wt% of triethanolamine, and an appropriate amount of 50 mmol/ml of Pt (illumination deposition mass fraction: 3 wt%) was added to the reaction system and subjected to ultrasonic treatment for 10 min. After vacuum pumping, the lamp is turned on to irradiate the mixed liquid. During the reaction, the temperature of the reaction solution was controlled at 279K by condensed water. After a period of reaction time, hydrogen was generated and analyzed by gas chromatography (GC-2014) using nitrogen as a carrier gas.
Example 1
1.1 heating 10g of melamine to 550 ℃ at the heating rate of 2 ℃/min, and preserving the temperature for 2 hours to obtain the bulk carbon nitride precursor.
1.2. 1.5 g of carbon nitride block synthesized at 550 ℃ was dispersed in 60ml of deionized water and stirred uniformly.
1.3. And (3) transferring the liquid obtained in the step (1.2) into a 100 ml reaction kettle, carrying out closed reaction at 200 ℃ for 10 hours, and carrying out centrifugal separation after the reaction to obtain white floccules.
1.4. And (3) centrifugally washing the product obtained in the step 1.3 for multiple times by using deionized water, and freeze-drying (namely freeze-drying) under the conditions that the vacuum degree is less than 20Pa and the freezing temperature is less than-20 ℃.
1.5. And (3) heating the white floccule obtained in the step (1.4) to 650 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, preserving heat for 2 hours, and naturally cooling along with the furnace to obtain a final carbon nitride product.
FIG. 1 is an SEM image of the obtained white flocs, wherein the obtained white flocs are in a fiber rod-like structure, FIG. 2 and FIG. 3 are SEM images of the finally obtained product, the finally obtained carbon nitride is in a hexagonal tube-like structure, the cross sections of the inner wall and the outer wall are both hexagonal, the length of the hexagonal tube is 50-70 μm, the side length of the cross section of the inner wall is 400-600 nm, and the wall thickness is 100-200 nm. Fig. 4 is an XRD pattern of the resulting white floc and the final carbon nitride product, and by comparison, it can be seen that the white floc has a crystal structure different from that of carbon nitride and is a new crystal structure, and after the secondary thermal polycondensation, the final product is restored to the crystal structure of carbon nitride again. FIG. 5 is a BET analysis spectrum of a final carbon nitride sample and a plate-shaped carbon nitride, and a comparison shows that the hexagonal tubular carbon nitride has a specific surface area of 189.9 cm2(g) specific surface area of flaky carbon nitride of 47.4cm2The specific surface area of hexagonal tubular carbon nitride is four times that of flaky carbon nitride. FIG. 6 is a graph showing the comparison of the photocatalytic hydrogen production of hexagonal tubular carbon nitride with that of tabular carbon nitride, and the comparison shows that the hydrogen production of hexagonal tubular carbon nitride is 9432.7. mu. mol g-1·h-1While hydrogen production of flake carbon nitride is only 1018.6μmol·g-1·h-1。
Example 2
Hexagonal tubular carbon nitride was prepared according to the method of example 1, except that: melamine was replaced by dicyandiamide while ensuring that 1.5 g of bulk carbon nitride could be obtained. The morphology of the obtained carbon nitride is similar to that of figure 3, and is a hexagonal tube shape, the length of the carbon nitride is about 50-65 μm, the side length of the cross section of the inner wall is 450-590 nm, and the wall thickness is 100-200 nm.
Example 3
Hexagonal tubular carbon nitride was prepared according to the method of example 1, except that: melamine was replaced by urea while ensuring that 1.5 g of bulk carbon nitride could be obtained. The morphology of the obtained carbon nitride is similar to that of figure 3, and is a hexagonal tube shape, the length of the carbon nitride is about 55-60 mu m, the side length of the cross section of the inner wall is 400-600 nm, and the wall thickness is 100-200 nm.
Example 4
4.1 heating 10g of melamine to 450 ℃ at the heating rate of 2 ℃/min, and preserving the temperature for 2 hours to obtain the bulk carbon nitride precursor.
4.2. 1.5 g of blocky carbon nitride synthesized at 450 ℃ was dispersed in 60ml of deionized water and stirred uniformly.
4.3. And (3) transferring the liquid obtained in the step (4.2) into a 100 ml reaction kettle, carrying out closed reaction at 200 ℃ for 10 hours, and carrying out centrifugal separation after the reaction to obtain white floccules.
4.4. And (4) centrifugally washing the product obtained in the step (4.3) for multiple times by using deionized water, and freeze-drying the product under the conditions that the vacuum degree is less than 20Pa and the freezing temperature is less than-20 ℃.
4.5. And (4) heating the white floccule obtained in the step 4.4 to 650 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, preserving heat for 2 hours, and naturally cooling along with the furnace to obtain the hexagonal tubular carbon nitride. The length of the hexagonal tube is about 60 mu m, the side length of the cross section of the inner wall is 400-570 nm, and the wall thickness is 100-150 nm.
Example 5
Hexagonal tubular carbon nitride was prepared according to the method of example 4, except that: the melamine is kept at 500 ℃ for 2 h. The SEM image of the obtained white floc is shown in FIG. 7, and after the bulk carbon nitride synthesized at 500 ℃ is hydrolyzed into a fibrous form and subjected to secondary thermal polycondensation at 650 ℃, the white floc is converted from a fibrous form into a hexagonal tubular carbon nitride as shown in FIG. 8. The obtained hexagonal tubular carbon nitride has a length of about 60 μm, a side length of a cross section of an inner wall of 400-600 nm, and a wall thickness of 180-200 nm.
Example 6
Hexagonal tubular carbon nitride was prepared according to the method of example 4, except that: the melamine is kept at 600 ℃ for 2 h. The SEM image of the obtained white floc is shown in FIG. 9, the bulk carbon nitride synthesized at 600 ℃ can be hydrolyzed into fiber, and after the secondary thermal polycondensation at 650 ℃, the white floc is converted from fiber to hexagonal tubular carbon nitride as shown in FIG. 10. The obtained hexagonal tubular carbon nitride has a length of about 60 μm, a side length of a cross section of an inner wall of 400-590 nm, and a wall thickness of 120-190 nm.
Example 7
7.1 heating 10g of melamine to 550 ℃ at the heating rate of 2 ℃/min, and preserving the heat for 4 hours to obtain the bulk carbon nitride precursor.
7.2. 1.5 g of carbon nitride block synthesized at 550 ℃ was dispersed in 60ml of deionized water and stirred uniformly.
7.3. And (3) transferring the liquid obtained in the step (7.2) to a 100 ml reaction kettle, carrying out closed reaction at 200 ℃ for 10 h, and carrying out centrifugal separation after the reaction to obtain white floccules.
7.4. And (4) centrifugally washing the product obtained in the step 7.3 for multiple times by using deionized water, and freeze-drying the product under the conditions that the vacuum degree is less than 20Pa and the freezing temperature is less than-20 ℃.
7.5. And (3) heating the white floccule obtained in the step 7.4 to 650 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, preserving heat for 2h, and then naturally cooling along with the furnace. The hexagonal tubular shape of the obtained sample is still maintained, the length of the hexagonal tubular carbon nitride is about 60 mu m, the side length of the cross section of the inner wall is 500-600 nm, and the wall thickness is 160-180 nm.
Example 8
8.1 heating 10g of melamine to 550 ℃ at the heating rate of 2 ℃/min, and preserving the temperature for 2 hours to obtain the bulk carbon nitride precursor.
8.2. 1.5 g of carbon nitride block synthesized at 550 ℃ was dispersed in 40 ml of deionized water and stirred uniformly.
8.3. And (3) transferring the liquid obtained in the step (8.2) into a 100 ml reaction kettle, carrying out closed reaction at 200 ℃ for 10 hours, and carrying out centrifugal separation after the reaction to obtain white floccules.
8.4. And (4) centrifugally washing the product obtained in the step (8.3) for multiple times by using deionized water, and freeze-drying the product under the conditions that the vacuum degree is less than 20Pa and the freezing temperature is less than-20 ℃.
8.5. And (3) heating the white floccule obtained in the step (8.4) to 650 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, preserving heat for 2h, and then naturally cooling along with the furnace. The hexagonal tubular shape of the obtained sample is still maintained, the length of the hexagonal tubular carbon nitride is about 64 mu m, the side length of the cross section of the inner wall is 450-560 nm, and the wall thickness is 170-200 nm.
Example 9
Hexagonal tubular carbon nitride was prepared according to the method of example 8, except that: the amount of water added during the hydrothermal reaction was adjusted to 70 ml. The obtained white floccule precursor is still fibrous, the final product still has a hexagonal tubular shape, the length of the hexagonal tubular carbon nitride is about 66 mu m, the side length of the cross section of the inner wall is 470-580 nm, and the wall thickness is 150-200 nm.
Example 10
10.1 heating 10g of melamine to 550 ℃ at the heating rate of 2 ℃/min, and preserving the temperature for 2 hours to obtain the bulk carbon nitride precursor.
10.2. 1.5 g of carbon nitride block synthesized at 550 ℃ was dispersed in 60ml of deionized water and stirred uniformly.
10.3. Transferring the liquid obtained in the step 10.2 into a 100 ml reaction kettle, sealing and reacting for 10 hours at 150 ℃, and centrifugally separating after the reaction to obtain white floccules.
10.4. And (4) centrifugally washing the product obtained in the step (10.3) for multiple times by using deionized water, and freeze-drying the product under the conditions that the vacuum degree is less than 20Pa and the freezing temperature is less than-20 ℃.
10.5. And (3) heating the white floccule obtained in the step 10.4 to 650 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, preserving heat for 2h, and then naturally cooling along with the furnace. The hexagonal tubular shape of the obtained sample is still maintained, the length of the hexagonal tubular carbon nitride is about 63 mu m, the side length of the cross section of the inner wall is 480-590 nm, and the wall thickness is 160-180 nm.
Example 11
11.1 heating 10g of melamine to 550 ℃ at the heating rate of 2 ℃/min, and preserving the temperature for 2 hours to obtain the bulk carbon nitride precursor.
11.2. 1.5 g of carbon nitride block synthesized at 550 ℃ was dispersed in 60ml of deionized water and stirred uniformly.
11.3. Transferring the liquid obtained in the step 11.2 into a 100 ml reaction kettle, sealing and reacting for 5 hours at 200 ℃, and centrifugally separating after the reaction to obtain white floccules.
11.4. And (4) centrifugally washing the product obtained in the step (11.3) for multiple times by using deionized water, and freeze-drying the product under the conditions that the vacuum degree is less than 20Pa and the freezing temperature is less than-20 ℃.
11.5. And (3) heating the white floccule obtained in the step (11.4) to 650 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, preserving heat for 2h, and then naturally cooling along with the furnace. The hexagonal tubular shape of the obtained sample is still maintained, the length of the hexagonal tubular carbon nitride is about 64 mu m, the side length of the cross section of the inner wall is 470-530 nm, and the wall thickness is 180-200 nm.
Example 12
Hexagonal tubular carbon nitride was prepared according to the method of example 11, except that: the hydrothermal reaction time during the hydrothermal reaction was increased from 5h to 15 h. The final product still has a hexagonal tubular shape, and the final shape of the product is not changed due to the prolonging of the hydrothermal reaction time. The hexagonal tubular carbon nitride has a length of about 60 μm, a side length of a cross section of the inner wall of 400 to 600 nm, and a wall thickness of 100 to 200 nm.
Example 13
13.1 heating 10g of melamine to 550 ℃ at the heating rate of 2 ℃/min, and preserving the heat for 2 hours to obtain the bulk carbon nitride precursor.
13.2. 1.5 g of carbon nitride block synthesized at 550 ℃ was dispersed in 60ml of deionized water and stirred uniformly.
13.3. Transferring the liquid in the step 13.2 into a 100 ml reaction kettle, sealing and reacting for 10 hours at 200 ℃, and centrifugally separating after the reaction to obtain white floccules.
13.4. And (4) centrifugally washing the product obtained in the step (13.3) for multiple times by using deionized water, and freeze-drying the product under the conditions that the vacuum degree is less than 20Pa and the freezing temperature is less than-20 ℃.
13.5. And (3) heating the white floccule obtained in the step (13.4) to 650 ℃ at a heating rate of 1 ℃/min under the protection of argon gas, preserving heat for 2 hours, and then naturally cooling along with the furnace. The hexagonal tubular shape of the obtained sample is still maintained, the length of the hexagonal tubular carbon nitride is about 65 mu m, the side length of the cross section of the inner wall is 470-540 nm, and the wall thickness is 160-180 nm.
Example 14
Hexagonal tubular carbon nitride was prepared according to the method of example 13, except that: the temperature rise rate in the second polycondensation process is increased from 1 ℃/min to 10 ℃/min. The increase of the temperature rise speed does not cause the collapse of the appearance, the obtained hexagonal tubular appearance of the sample is still maintained, the length of the hexagonal tubular carbon nitride is about 60 mu m, the side length of the cross section of the inner wall is 430-570 nm, and the wall thickness is 120-180 nm.
Example 15
15.1 heating 10g of melamine to 550 ℃ at the heating rate of 2 ℃/min, and preserving the temperature for 2 hours to obtain the bulk carbon nitride precursor.
15.2. 1.5 g of blocky carbon nitride synthesized at 550 ℃ was dispersed in 60ml of deionized water and stirred uniformly.
15.3. And (3) transferring the liquid obtained in the step (15.2) into a 100 ml reaction kettle, carrying out closed reaction for 10 hours at the temperature of 200 ℃, and carrying out centrifugal separation to obtain white floccules.
15.4. And (4) centrifugally washing the product obtained in the step (15.3) for multiple times by using deionized water, and freeze-drying the product under the conditions that the vacuum degree is less than 20Pa and the freezing temperature is less than-20 ℃.
15.5. And (3) heating the white floccule obtained in the step 15.4 to 450 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, preserving heat for 2h, and then naturally cooling along with the furnace. The hexagonal tubular shape of the obtained sample is still maintained, the length of the hexagonal tubular carbon nitride is about 54 mu m, the side length of the cross section of the inner wall is 460-580 nm, and the wall thickness is 100-200 nm.
Example 16
Hexagonal tubular carbon nitride was prepared according to the method of example 15, except that: the holding temperature during the second polycondensation was increased from 550 ℃ to 750 ℃. The hexagonal tubular shape of the obtained sample is still maintained, the length of the hexagonal tubular carbon nitride is about 56 micrometers, the side length of the cross section of the inner wall is 440-560 nm, and the wall thickness is 140-160 nm.
Example 17
17.1 heating 10g of melamine to 550 ℃ at the heating rate of 2 ℃/min, and preserving the temperature for 2 hours to obtain the bulk carbon nitride precursor.
17.2. 1.5 g of blocky carbon nitride synthesized at 550 ℃ was dispersed in 60ml of deionized water and stirred uniformly.
17.3. Transferring the liquid obtained in the step 17.2 into a 100 ml reaction kettle, sealing and reacting for 10 hours at 200 ℃, and performing centrifugal separation to obtain white floccule.
17.4. And (4) centrifugally washing the product obtained in the step (17.3) for multiple times by using deionized water, and freeze-drying the product under the conditions that the vacuum degree is less than 20Pa and the freezing temperature is less than-20 ℃.
17.5. And (3) heating the white floccule obtained in the step (17.4) to 650 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, preserving heat for 1 h, and then naturally cooling along with the furnace. The hexagonal tubular shape of the obtained sample is still maintained, the length of the hexagonal tubular carbon nitride is about 64 mu m, the side length of the cross section of the inner wall is 430-530 nm, and the wall thickness is 160-190 nm.
Example 18
Hexagonal tubular carbon nitride was prepared according to the method of example 17, except that: the holding time in the second polycondensation process was increased from 1 h to 4 h. The obtained sample does not collapse along with the prolonging of the thermal polycondensation time, the hexagonal tubular shape of the obtained sample is still maintained, the length of the hexagonal tubular carbon nitride is about 61 mu m, the side length of the cross section of the inner wall is 430-520 nm, and the wall thickness is 140-190 nm.
The results of photocatalytic hydrogen production performance tests on the hexagonal tubular carbon nitride obtained in each example show that the hydrogen production amount of the hexagonal tubular carbon nitride in each example is 8878.6 mu molg-1·h-1To 9432.7. mu. mol g-1·h-1Wherein the product obtained in example 17 had the lowest hydrogen production of 8878.6. mu. mol. g-1·h-1The highest hydrogen yield of the product obtained in example 1 was 9432.7. mu. mol. g-1·h-1。
Comparative example 1
A carbon nitride product was prepared according to the method of example 1 except that no hydrothermal treatment was performed, and the steps were:
1.1 heating 10g of melamine to 550 ℃ at the heating rate of 2 ℃/min, and preserving the temperature for 2 hours to obtain the bulk carbon nitride precursor.
1.2. And (3) heating the block carbon nitride obtained in the step (2.1) to 650 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, preserving heat for 2 hours, and naturally cooling along with the furnace to obtain a carbon nitride product, wherein the carbon nitride product is shown in figure 11 and is in a sheet shape.
Comparative example 2
A carbon nitride product was prepared according to the method of example 1, except that: the thermal polycondensation temperature of melamine was adjusted from 550 ℃ to 650 ℃ and 400 ℃ respectively.
The results show that the SEM image of the product obtained after hydrothermal reaction of the bulk carbon nitride obtained at 650 ℃ is shown in FIG. 12, and it can be seen that the bulk carbon nitride is not assembled by hydrolysis after hydrothermal treatment, the bulk structure is still maintained, and finally the obtained carbon nitride cannot form a hexagonal tube shape.
And the SEM image of the product of the bulk carbon nitride obtained at 400 ℃ after the hydrothermal reaction is fibrous as shown in FIG. 13, and the SEM image of the finally obtained carbon nitride product is shown in FIG. 14, so that the collapse of the hexagonal tubular shape of the finally obtained product can be seen.
It can be seen that the polycondensation temperature of melamine has a significant effect on the morphology of the product.
Comparative example 3
A carbon nitride product was prepared according to the method of example 1, except that: the amount of deionized water added in the hydrothermal process is adjusted from 60ml to 25 ml and 80ml respectively, the final products have no hexagonal tubular appearance, the appearance of the 25 ml obtained product is blocky, and when 80ml is obtained, the carbon nitride is completely hydrolyzed under high temperature and high pressure.
Comparative example 4
A carbon nitride product was prepared according to the method of example 1, except that: the heating temperature in the hydrothermal process is adjusted from 200 ℃ to 140 ℃ and 220 ℃ respectively, the result shows that no hexagonal tubular shape is formed, the shape of the product at 140 ℃ is flaky, carbon nitride is hydrolyzed completely at 220 ℃, and no sample is collected.
Comparative example 5
A carbon nitride product was prepared according to the method of example 1, except that: heating the white floccule to 400 ℃ and 800 ℃ respectively at a heating rate of 5 ℃/min under the protection of argon gas, and preserving heat for 2 h.
At a temperature of 400 ℃, the obtained sample cannot realize complete polycondensation, and the sample is not carbon nitride; at a temperature of 800 c, the collapse was complete and the decomposition was carried out at high temperature, and no sample was collected.
Comparative example 6
A carbon nitride product was prepared according to the method of example 1, except that: the hydrothermal process solvent was adjusted from deionized water to ethanol, and the result is shown in fig. 15, where the carbon nitride maintained a blocky morphology and did not hydrolyze.
Comparative example 7
7.1 10g of melamine are dispersed in 60ml of deionized water and stirred well.
7.2. Transferring the liquid obtained in the step 7.1 into a 100 ml reaction kettle, sealing and reacting for 10 hours at 200 ℃, and centrifugally separating after the reaction to obtain white floccules.
7.3. And (3) centrifugally washing the product obtained in the step (7.2) for multiple times by using deionized water, and freeze-drying the product under the conditions that the vacuum degree is less than 20Pa and the freezing temperature is less than-20 ℃.
7.4. And (4) heating the white floccule obtained in the step 7.3 to 650 ℃ at a heating rate of 5 ℃/min under the protection of argon gas, preserving heat for 2h, and then naturally cooling along with the furnace. The obtained white floccule precursor is polygonal as shown in fig. 16, after the secondary calcination treatment, the hexagonal tubular shape collapses, and the final product is mainly flaky as shown in fig. 17.

Claims (5)

1. A preparation method of hexagonal tubular carbon nitride is characterized by comprising the following steps:
(1) heating the nitrogen-containing organic precursor to 450-600 ℃ for calcining to obtain blocky carbon nitride;
(2) dispersing the blocky carbon nitride in water, and carrying out hydrothermal reaction at 150-200 ℃ to obtain floccules;
(3) heating the floccule to 450-750 ℃ for calcining to obtain hexagonal tubular carbon nitride;
the obtained hexagonal-tube-shaped carbon nitride contains carbon nitride as an effective component, is hexagonal-tube-shaped, and has hexagonal cross sections on the outer wall and the inner wall;
in the step (1), the nitrogen-containing organic precursor is melamine, dicyandiamide or urea;
in the step (2), the mass ratio of the blocky carbon nitride to the water is 0.02-0.05: 1;
in the step (3), the calcination is carried out under the protection of gas, and the protection gas is nitrogen or inert gas.
2. The method of claim 1, wherein: the hexagonal tubular carbon nitride has a length of 50-70 μm, a side length of a cross section of the inner wall of 400-600 nm, and a wall thickness of 100-200 nm.
3. The method of claim 1, wherein: in the step (1), the calcination is carried out in an air atmosphere; in the step (2), the hydrothermal reaction is carried out in a reaction kettle in a closed environment.
4. The method of claim 1, wherein: in the step (1), heating to 450-600 ℃ at a heating rate of 2-5 ℃/min; in the step (3), the temperature is increased to 450-750 ℃ at a temperature increasing speed of 1-10 ℃/min.
5. The method of claim 1, wherein: calcining for 2-4 h at 450-600 ℃ in the step (1); in the step (2), reacting for 5-15 h at 150-200 ℃; in the step (3), calcining is carried out for 1-4 h at 450-750 ℃.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103214878A (en) * 2013-04-02 2013-07-24 江苏大学 Preparation method of graphite type carbon nitride-ionic liquid composite material
CN106744742A (en) * 2016-11-11 2017-05-31 天津大学 Many shell graphite phase carbon nitride hollow nano-spheres and its synthetic method and application
CN107715903A (en) * 2017-10-11 2018-02-23 肇庆市华师大光电产业研究院 A kind of method for being acidified assisting alcohol-hydrothermal method and preparing high-efficiency silicon nitride carbon nano rod photochemical catalyst

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103214878A (en) * 2013-04-02 2013-07-24 江苏大学 Preparation method of graphite type carbon nitride-ionic liquid composite material
CN106744742A (en) * 2016-11-11 2017-05-31 天津大学 Many shell graphite phase carbon nitride hollow nano-spheres and its synthetic method and application
CN107715903A (en) * 2017-10-11 2018-02-23 肇庆市华师大光电产业研究院 A kind of method for being acidified assisting alcohol-hydrothermal method and preparing high-efficiency silicon nitride carbon nano rod photochemical catalyst

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Template-free large-scale synthesis of g-C3N4 microtubes for enhanced visible light-driven photocatalytic H2 production;Chao Zhou, et al.;《Nano Research》;20180522;第3462-3468页 *

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